Stacked plate heat exchangers typically comprise a plurality of plate pairs stacked one on top of the other with each plate pair having opposed inlet and outlet openings such that when the plate pairs are stacked together, the inlet and outlet openings align to form inlet and outlet manifolds and thereby establish communication between fluid channels formed inside each plate pair. The plate pairs are usually joined together by brazing. However, as the plate pairs tend to be unsupported in the area of the manifolds, the heat exchanger in the area of the inlet and outlet openings tends to distort under the pressure of the fluid flowing therethrough and will often expand like an accordion or “bellows” in the manifold region. The distortion that occurs in the manifold regions of the heat exchanger tends to lead to premature failure or cracking and leaking in the heat exchanger.
Similarly, in in-tank oil coolers (ITOC) (cross-section of a portion of an ITOC is shown in FIG. 1), under internal oil pressure, the header expands primarily due to the force acting on the unsupported area of the bottom plate. Although turbulizers are present in the channel (though not shown in FIG. 1), the turbulizers end at the header bubble, and hence can only provide limited support to the header region. This expansion, similar to how a bellows would expand, leads to eventual failure in the core plate bubble under high pressure. This failure location is typically located either in the top or bottom channel due to the change in local stiffness because of the presence of the fitting and bottom reinforcement plate.
For applications that require higher durability, the core plate bubbles are replaced with washers (also referred to as spacers) as shown FIG. 2. The higher durability is achieved not only by the elimination of the bubbles but by extending the washer diameter such that it overlaps the area of the core plate to which the turbulizer brazes. This increases the vertical rigidity of the header region, making is less susceptible to vertical expansion under pressure. The drawback to such a design is that it makes it more complicated for assembly and increases the final cost of the part.
Another approach used to reinforce the inlet and outlet areas of a heat exchanger is to use exterior clamps or brackets that are brazed to the outside of the heat exchanger to keep it from expanding under pressure. Another further approach is to insert perforated or slotted tubes through all of the aligned inlet and outlet openings of each plate, the tubes being brazed to the peripheries of the respective inlet and outlet openings. However, such approaches as described above, can be costly and can increase overall manufacturing process and costs associated with the particular heat exchanger.
U.S. Pat. No. 5,794,691 (Evans et al.) discloses a heat exchanger made from a plurality of stacked plate pairs wherein the inlet and outlet openings that form the manifolds include opposed flange segments formed on the inner peripheral edges of the openings. The flange segments extend inwardly and are joined together when the plates are stacked together to prevent expansion of the manifolds when under pressure.
U.S. Pat. No. 8,678,076 B2 (Shore et al.) discloses a plate type heat exchanger having a plurality of stacked plate pairs. Each plate pair has opposed manifold members with respective inlet and outlet openings that are in registration to form respective inlet and outlet manifolds for the flow of a first fluid through a first set of fluid channels formed by the plate pairs. The manifold members spacing the plate pairs apart to form a second set of transverse flow channels for the flow of a second fluid. Each plate has a peripheral edge portion which seals the plates together to form the first set of fluid channels therebetween. A protrusion member is formed proximal to each of the manifold members, each protrusion member having a mating surface such that the protrusion members on the second plate of one plate pair align and abut with the protrusion members on the first plate of an adjacent plate pair thereby reinforcing and strengthening the manifold region of the heat exchanger to prevent the deformation or accordion of the manifold under pressure.
There is a need in the art for heat exchanger plates that can help to form a rigid structure along the height of the heat exchanger that allows the bottom and top core plates to better withstand the pressure load of a fluid flowing therethrough. In addition, there is a need in the art for a heat exchanger plate that can to eliminate the need to use washers between core plates in the header region and to increase the burst strength of the heat exchanger. Further, there is a need in the art for a heat exchanger having such heat exchanger plates.
Similar reference numerals may have been used in different figures to denote similar components.